Macro text_io::try_scan

macro_rules! try_scan {
    ($pattern:expr, $($arg:expr),*) => { ... };
    ($input:expr => $pattern:expr, $($arg:expr),*) => { ... };
    (@question_mark: $($e:tt)+) => { ... };
    (@unwrap: $($e:tt)+) => { ... };
    (@impl $action:tt; $input:expr => $pattern:expr, $($arg:expr),*) => { ... };
}

use text_io::try_scan;

fn parser() -> Result<i32, Box<dyn std::error::Error>> {
    let i: i32;
    let text = "The answer is 42!";

    try_scan!(text.bytes() => "The answer is {}!", i);

    assert_eq!(i, 1);
    Ok(i)
}